CN111132749A - System and method for preventing membrane fouling in reverse osmosis purification system by using hydrodynamic cavitation - Google Patents

Abstract

The present disclosure provides a method for preventing fouling of a membrane in a fluid treatment system having at least one membrane. The method describes hydrodynamic cavitation of a fluid stream prior to injecting the fluid stream into the fluid treatment system and through the at least one membrane, wherein after undergoing hydrodynamic cavitation in the cavitation reactor, solid components in the fluid change their (i) molecular structure, (ii) charge, or both, such that the components repel each other and disperse around the edges of the membrane to prevent fouling. A system for preventing fouling of a membrane in a fluid treatment system having at least one membrane is also provided.

Description

System and method for preventing membrane fouling in reverse osmosis purification system by using hydrodynamic cavitation

Cross Reference to Related Applications

This application claims the benefit of U.S. provisional application No. US 62503313 filed on 8/5/2017.

Technical Field

The present invention relates generally to remediation of fluids, and more particularly to a system and method for preventing or eliminating membrane fouling and/or scaling using hydrodynamic cavitation, as the present invention relates generally to fluid treatment systems, and more particularly to Reverse Osmosis (RO) systems.

Background

The many diverse activities of mankind produce countless waste and by-products. As the environmental, health, and industrial impact of pollutants increases, it becomes increasingly important to develop new methods for quickly and efficiently removing a wide variety of pollutants from contaminated water bodies and other liquids. The goal of so-called remediation is to reduce or eliminate contaminants and other unsafe substances from the fluid.

There are many repair methods. Some bioprocessing techniques include bioaugmentation, bioaeration, bio-aeration, bio-rinsing, and phytoremediation. Some chemical treatment techniques include ozone and oxygen injection, chemical precipitation, membrane separation, ion exchange, carbon absorption, aqueous chemical oxidation, and surfactant enhanced recovery. Some chemical techniques may be implemented using nanomaterials. Physical processing techniques include, but are not limited to, pumping and processing, air sparging, and two-phase extraction.

One example of a remediation technology that incorporates the use of membrane technology is Reverse Osmosis (RO), which is a water purification technology that uses a semi-permeable membrane, a membrane that allows water molecules to pass through but does not allow most of the dissolved salts, organics, bacteria, and pyrogens to pass through, to remove ions, molecules, and larger particles from contaminated water by pushing the water under pressure through the semi-permeable membrane.

RO works by using a high pressure pump to increase the pressure on the salt side of the RO and force water across the semi-permeable membrane, leaving almost all of the dissolved salts in the retentate stream. Demineralized water that is demineralized or deionized is referred to as permeate. The water stream carrying the concentrated contaminants that have not passed through the RO membrane is referred to as the retentate (or concentrate) stream. As feed water enters the RO membrane under pressure, water molecules pass through the semi-permeable membrane and salts and other contaminants are not allowed to pass through and exit through the concentrate stream. In some RO systems, the concentrate stream may be returned to the RO system via the feed water and recycled through the RO system. The water that passes through the RO membrane is referred to as permeate or product water and typically about 95% to 99% of the dissolved salts are removed therefrom.

Reverse osmosis can remove various types of dissolved and suspended matter (including bacteria) from water and is used in both industrial processes and drinking water production. The result is that the solute is trapped on the pressurized side of the membrane and pure solvent is allowed to flow to the other side. To be "selective," the membrane should not allow large molecules or ions to pass through the pores (holes), but should allow smaller components of the solution (such as solvent molecules) to pass freely. Many times solutes include silica, barium and other solids. U.S. Pat. No. 4,277,344 discloses examples of RO membranes describing an aramid membrane which is the interfacial reaction product of an aromatic polyamine having at least two primary amine substituents and an aromatic acyl halide having at least three acyl halide substituents.

While RO is itself highly efficient, it is problematic due to so-called "membrane fouling" that occurs when contaminants accumulate on the membrane surface, which effectively plugs the membrane and significantly reduces its remediation effectiveness. Fouling typically occurs in the front end of the RO system and results in a higher pressure drop across the RO system and therefore a lower permeate flow. Fouling comes mainly from three sources, namely: (i) particles in the feed water (e.g., solutes or concentrates); (ii) accumulation of poorly soluble minerals; and (iii) byproducts of microbial growth. Due to fouling, the membranes must be cleaned often, which is expensive and reduces the efficiency of the system as a whole due to the need for more maintenance. Furthermore, cleaning the membrane is often expensive and results in a short service life of the membrane element. This is especially true when more than one fouling condition exists, which can irreversibly foul the membrane, and the only suitable solution is to completely replace the membrane element.

Several pretreatment methods using mechanical and chemical treatments have been proposed to reduce membrane fouling. For example, the anti-fouling agent may be injected into the supply source before reaching the RO membrane. However, this only delays the fouling formation process. This delay is sufficient to avoid precipitation of calcium carbonate and calcium sulfate on the membrane surface. Because this delay lasts for a limited period of time, fouling may occur on the system that is shut down. Another example is that a dispersant may be injected into the feed water. The dispersant prevents fine suspended solids from coagulating and falling onto the membrane surface. Proper use of the dispersant can minimize fouling due to the problem of difficult pre-filtration of the particles. However, dispersants have the same problems as antifouling agents. For example, U.S. patent No. 6365101 discloses a method for inhibiting scale deposition in an aqueous system comprising at least one of a multivalent metal silicate and a multivalent metal carbonate, wherein the aqueous system has a pH of at least about 9, and wherein the average particle size of the anti-scalant is less than about 3 microns.

Another pre-treatment solution includes the use of a multi-media filter to help prevent fouling. Multi-media filters typically contain three layers of media consisting of anthracite, sand and garnet, with a gravel support layer at the bottom. This filter media arrangement allows the largest dust particles to be removed near the top of the media bed, while the smaller dust particles are retained deeper in the media. This allows the entire bed to act as a filter, allowing longer filter run times and more efficient particulate removal. Additional methods include the use of microfiltration membranes, water softeners that aid in exchanging scale-forming ions for non-scale-forming ions, intercalation of sodium bisulfite, and granular activated carbon.

However, these current pretreatment methods can be costly and fouling can still occur at a rate that can be considered low. In addition, regardless of the degree of care, fouling eventually occurs to some extent given the very fine RO membrane pore size, regardless of how effective your pretreatment and cleaning plan is.

Thus, a post-treatment method has also been proposed. For example, methods have been proposed to alter the membrane surface charge to repel certain solutes, as have been disclosed for certain coatings on the membrane surface. For example, U.S. patent No. 6913694 describes a selective membrane that is a composite polyamide reverse osmosis membrane in which a hydrophilic coating has been applied to the polyamide layer of the membrane, the hydrophilic coating being made by: (i) applying to the membrane an amount of a multifunctional epoxy compound comprising at least two epoxy groups, and (ii) then crosslinking the multifunctional epoxy compound in a manner to produce a water-insoluble polymer.

Further, U.S. patent No. 9089820 describes a selective membrane that is a composite polyamide reverse osmosis membrane having a hydrophilic coating made by covalently bonding a hydrophilic compound to the polyamide membrane, the hydrophilic compound comprising (i) a reactive group suitable for direct covalent bonding to the polyamide membrane, the reactive group being at least one of a primary amine and a secondary amine; (ii) a non-terminal hydroxyl group; and (iii) an amide group. In another embodiment, the hydrophilic compound comprises (i) a reactive group suitable for direct covalent bonding to a polyamide membrane, the reactive group being at least one of a primary amine and a secondary amine; (ii) a hydroxyl group; and (iii) an amide group directly linked to the hydroxyl group through one of an alkyl group and an alkenyl group.

However, these methods have achieved only moderate success, can be expensive, and also make cleaning the membrane more difficult. Accordingly, there is a need for an improved system and method for preventing fouling of membranes. One potential solution is to use hydrodynamic cavitation before contaminated water is fed through the RO membrane.

Cavitation is generally the formation of a vapor cavity in a liquid, which forms a small liquid-free zone. In engineering terms, the term cavitation is used in a narrow sense, i.e. to describe a vapor-filled cavity formed in the interior or on the boundary of a solid at a local pressure reduction produced by the dynamic action of the liquid system.

In hydrodynamic cavitation, decontamination can be achieved by using submerged jets that trigger hydrodynamic cavitation events in the liquid. These cavitation events drive chemical reactions by generating strong oxidants and reductants and effectively breaking down and destroying contaminating organic compounds as well as some inorganic species. These same cavitation events not only physically disrupt or break the cell walls or outer membranes of microorganisms (such as E.coli and Salmonella) and larvae (such as zebra mussel larvae), but also produce bactericidal compounds (such as peroxides, hydroxyl radicals, etc.) that help destroy these organisms. After the cell wall or outer membrane is disrupted, the internal cellular components are susceptible to oxidation.

Cavitation techniques have been used in a wide variety of industrial and ecological remediation environments, including, but not limited to, agriculture, mining, pharmaceuticals, food and beverage manufacturing and processing, fisheries, oil and gas production and processing, water treatment, and alternative fuels. Due to such a wide field of use, companies are increasingly eager to further develop cavitation technology.

Some examples include: the use of a rotary spray nozzle for cleaning and maintenance purposes is disclosed in U.S. Pat. No. 5,749,384(Hayasi et al) and U.S. Pat. No. 4,508,577(Conn et al). The Hayasi apparatus employs a drive mechanism that enables the spray nozzle itself to travel, rotate and oscillate up and down. Conn et al describe rotating a cleaning head comprising at least two jet forming devices for cleaning the inner side walls of a conduit.

In many cases, these current hydrodynamic cavitation techniques aim to reduce the particle distribution size of suspended solids, such as that often found in RO to be responsible for membrane fouling. Despite advances in utilizing cavitation, little to no combination of cavitation with RO can be used, which can take advantage of the benefits of cavitation to help prevent membrane fouling. Therefore, there is a need for a new system and method to incorporate hydrodynamic cavitation into RO to create an RO process that is more efficient and effective and also reduces the potential for membrane fouling.

Disclosure of Invention

The following summary is provided to provide a basic understanding of some aspects and features of the invention. This summary is not an extensive overview of the invention, and thus, it is not intended to identify key or critical elements of the invention or to delineate the scope of the invention. Its sole purpose is to present some concepts of the invention in a simplified form as a prelude to the more detailed description that is presented later.

To achieve the foregoing and other aspects and in accordance with the purpose of the present invention, a system and method for preventing fouling of a membrane in a fluid treatment system.

In an embodiment of the present invention, there is provided a system for preventing membrane fouling in a fluid treatment system having at least one membrane, the system comprising: a hydrodynamic cavitation reactor for cavitating the fluid stream prior to injecting the fluid stream into the fluid treatment system and through the at least one membrane; wherein after undergoing hydrodynamic cavitation in the cavitation reactor, solid components in the fluid change their (i) molecular structure, (ii) charge, or both, such that the components repel each other and disperse around the edges of the membrane to prevent fouling.

In an embodiment of the present invention, a method for preventing fouling of a membrane in a fluid treatment system having at least one membrane is provided. The method comprises the following steps: cavitating the fluid stream hydraulically prior to injecting the fluid stream into the fluid treatment system and through the at least one membrane; wherein after undergoing hydrodynamic cavitation in the cavitation reactor, solid components in the fluid change their (i) molecular structure, (ii) charge, or both, such that the components repel each other and disperse around the edges of the membrane to prevent fouling.

Such a method is useful in areas such as industrial and ecological remediation environments, including, for example, municipal drinking water, desalination, agriculture, mining, pharmaceuticals, food and beverage manufacturing and processing, fisheries, oil and gas production and processing, water treatment, and alternative fuels. In particular, the system and method are useful in arrangements utilizing filters having membranes that are prone to fouling, such as in reverse osmosis systems and water desalination.

It is a further object of the present invention to provide a new and improved system and method which is easy and inexpensive to construct.

Other features, advantages, and aspects of the invention will become more apparent and more readily appreciated from the following detailed description, which is to be read in connection with the accompanying drawings.

Drawings

The present invention is illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings and in which like reference numerals refer to similar elements and in which:

FIG. 1 is a schematic view of a fluid remediation system incorporating hydrodynamic cavitation in accordance with an embodiment of the present invention;

FIG. 2 is a block diagram of a fluid remediation system incorporating hydrodynamic cavitation in accordance with an embodiment of the present invention;

FIG. 3 is a step-by-step flow diagram of a method for performing fluid remediation incorporating hydrodynamic cavitation in accordance with an embodiment of the present invention;

FIG. 4 is a front view of a membrane for use in reverse osmosis according to one embodiment of the present invention;

FIG. 5 is a flow diagram illustrating an example method for cavitation-based water remediation, according to one embodiment of the present disclosure;

FIG. 6 is a schematic diagram detailing a use case for remediation in a farm using a fluid remediation system, according to an embodiment of the invention;

FIG. 7 illustrates data obtained from test cases for performing a repair using the systems and methods provided herein;

FIG. 8 is a front view of a reactor plate used in the hydrodynamic cavitation system in accordance with an embodiment of the present invention; and is

FIG. 9 is a schematic diagram of a fluid remediation system utilizing hydrodynamic cavitation and an intelligent platform and automated hardware/software arrangement, according to one embodiment of the invention.

The illustrations in the drawings are not necessarily drawn to scale unless otherwise indicated.

Detailed Description

The invention is best understood by reference to the detailed drawings and description set forth herein.

Embodiments of the invention will be discussed below with reference to the accompanying drawings. However, those skilled in the art will readily appreciate that the detailed description given herein with respect to these figures is for explanatory purposes as the invention extends beyond these limited embodiments. For example, it should be appreciated that those skilled in the art will recognize a variety of alternative and suitable approaches to achieve the functionality of any given detail described herein, in view of the teachings of the present invention, and in accordance with the needs of a particular application, in addition to those particular implementations in the following embodiments described and illustrated. That is, there are many modifications and variations of the present invention that are too numerous to list, but fall within the scope of the invention.

It is to be further understood that this invention is not limited to the particular methodology, compounds, materials, manufacturing techniques, uses, and applications described herein, as these may vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the present invention. It must be noted that, as used herein and in the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "an element" means one or more of the element and includes equivalents thereof known to those skilled in the art. Similarly, for another example, reference to "a step" or "a device" means one or more steps or devices and may include sub-steps as well as sub-devices. All conjunctions used should be understood in the most inclusive sense possible. Thus, unless the context clearly dictates otherwise, the word "or" should be understood to have the definition of a logical "or" rather than the definition of a logical "exclusive or". Structures described herein are also to be understood as meaning functional equivalents of such structures. Language that may be construed to express approximate meaning should be understood as such unless the context clearly dictates otherwise.

As used herein, the term "concentrate stream" shall refer to the water stream that carries the concentrated contaminants that have not passed through the RO membrane. The retentate water may also be referred to herein as a "retentate stream".

As used herein, the term "contaminated water" shall refer to water molecules bound to dissolved salts, organic matter, bacteria and pyrogens.

As used herein, the term "permeate water" shall refer to desalinated water that is demineralized or deionized after passing through an RO membrane. Permeate water may also be referred to herein as "product water".

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Preferred methods, techniques, devices, and materials are described, but any methods, techniques, devices, or materials similar or equivalent to those described herein can be used in the practice or testing of the present invention. Structures described herein are also to be understood as meaning functional equivalents of such structures. The invention will now be described in detail with reference to embodiments thereof as illustrated in the accompanying drawings.

Those of skill in the art will readily appreciate in light of the teachings of the present invention that any of the foregoing steps and/or system modules may be appropriately replaced, reordered, removed, and additional steps and/or system modules may be inserted as desired for a particular application, and that the system of the foregoing embodiments may be implemented using any of a variety of suitable processes and system modules, and is not limited to any particular computer hardware, software, middleware, firmware, microcode, etc. For any method steps described in this application that may be performed on a computing machine, a typical computer system, when suitably configured or designed, may be used as the computer system in which the aspects of the invention are implemented.

Although exemplary embodiments of the present invention will be described with reference to certain industries in which cavitation may be applied, skilled artisans will recognize that embodiments of the present invention are applicable to any type of application in which cavitation is beneficial.

The system and method of the present invention prevents membrane fouling and repairs fluids. The system is configured to alter the molecular and/or structural properties of organic and inorganic concentrate materials that normally clog or foul membranes in the filtration system. The detailed components and specific embodiments of the abatement system may be best understood by further understanding the cavitation phenomena used to drive the physical and chemical abatement reactions. Due to the large pressure drop in the flow, microbubbles grow in the pressure drop region and collapse in the pressure rise region. When subjected to cavitation, various molecules in the liquid dissociate and form free radicals, which are powerful oxidizing or reducing agents. For example, in aqueous liquids, water dissociation to form hydroxyl radicals occurs under intense cavitation due to the growth and collapse of microbubbles. Similar dissociation of other molecules may occur due to cavitation in aqueous solutions as well as non-aqueous liquids and solutions, thereby generating free radicals that similarly contribute to the decontamination reactions described herein. Moreover, cavitation generated in any liquid environment will cause physical destruction of contaminants without concern for the generation of specific free radicals. The method and system of the present invention will be applicable to all fluid environments that include contaminants that are susceptible to decomposition by the physical and/or chemical effects of cavitation employed.

The inventors have found that using the systems and methods described herein, the concentrate can change form and does not foul the membranes of the RO membranes, as described herein. The inventors have also found that the system and method can be used for other types of filtration using membrane technology.

Referring now to FIG. 1, a schematic diagram of a fluid remediation system incorporating hydrodynamic cavitation in accordance with an embodiment of the present invention is generally designated 100. The system 100 defines a hydrodynamic cavitation system 158 coupled to the inlet 102 and various outlets 104A-E and RO membranes 160. In the current embodiment, there is one inlet 102 and 5 outlets 104A-E, but in alternative embodiments, there may be a greater or lesser number of inlets and/or outlets.

Still referring to fig. 1, the rehabilitation section 101 is configured to introduce contaminated water into the system 100 along a path indicated at 162 using the pump 126. The contaminated water passing through the remediation channel 101 may initially be raw water, brown or black, and may contain sediment, contaminants, etc., and will be introduced into the hydrodynamic cavitation system 158 by the pump 126 coupled to the hydrodynamic cavitation system 158. The pump 126 is used to supply contaminated water to the hydrodynamic cavitation system 158 for treatment.

In the current embodiment, there is only one pump 148 configured to operate at high pressure. In alternative embodiments, the pump 148 may be operated at different pressures to account for the concentration of different types of contaminants (e.g., arsenic, lead, radium, cadmium, and zinc) found in the contaminated water. In even other alternative embodiments, more than one pump 148 may be used.

While a simple rectangular can is shown in fig. 1, it should be understood that a variety of sizes, shapes, container locations, and numbers of parts of various sizes may be employed.

Still referring to fig. 1, starting now at inlet 102, the system includes a sensor housing 106, a first valve 108, a plurality of injector coils 110, an additive port 112, and a flow meter 114. As used herein, this region of the system may be referred to as a "pre-cavitation zone" or a "mixing zone". The system may further include a first air injector 116, and a second sensor array 118, followed by a swirl plate 146 and a second air injector 120. Additional sensors (e.g., pressure sensor 124) and a second valve 122 are also shown. The repair path 101 then continues to the exit 104. As used herein, this region of the system may be referred to herein as a "cavitation zone" 144.

Still referring to fig. 1, the sensor housing 106 is positioned proximate the inlet 102 and communicatively coupled to the remediation pathway 101 such that the remediated contaminated water is tested and monitored prior to entering the pre-cavitation zone. In an alternative embodiment of the invention, a divergent path 128 and valve 108 are provided so that a sample of the repair fluid is ejected for testing. An access path 132 is further provided for injecting the test fluid back into the repair channel 101 via a valve 134 (e.g., a choke valve) coupled to the access path 132. The sensor housing 106 may include an array of sensors for automation, characterization, and monitoring of a process. For example, the sensor array may include many different components, including mechanical sensors, electronics, analytical and chemical sensors, a control system, a telemetry system, and software that allows the sensors to communicate with a Programmable Logic Controller (PLC), which will be discussed in more detail in connection with fig. 9.

Still referring to fig. 1, in the current embodiment of the present invention, the sensor housing 106 may include mechanical sensors, pressure gauges and flow meters to measure flow rate, electronic sensors to measure various parameters such as pressure, specific gravity, presence of liquid (level gauges and interface probes), pH, temperature and conductivity, and analytical sensors to measure chemical parameters such as contaminant concentration. Some examples of analytical sensors include pH probes and optical sensors for colorimetric measurements. The control system working in conjunction with the sensors includes a PLC and other electronic microprocessor devices. The control system is capable of receiving sensor inputs, processing information, and triggering specific actions. These will be discussed in more detail in connection with fig. 9.

Still referring to fig. 1, a plurality of conduits 136 are fluidly coupled to the repair channel 101, the conduits 136 being configured for injecting certain substances into the repair channel 101. By way of example, different types and combinations of precursor compounds in solid, liquid or gas phase may be employed depending on the type of fluid treatment process selected, the contaminants to be treated, the existing water quality, the desired water quality, and other variables. Precursor compound 140 can be pumped or injected into repair channel 101 by pumps 138A-E. In the current embodiment, five pumps 138A-E are used, but in alternative embodiments, more than five pumps may be used. The precursor compound 140 may be a feedstock, but may also include replaceable cartridges, line feeds, or other similar chemical inputs, and for larger water streams, include a large supply of various feedstocks and precursor feed materials.

Still referring to fig. 1, exemplary precursor compounds 140 include compounds that may include halide salts (such as fluorine, chlorine, bromine, iodine), sulfate salts, sodium, potassium, and the like, introduced as solids, or dissolved in water or some other solvent. Liquid raw materials such as ozone, hydrogen peroxide, peroxy acid, aqueous salt solution, chlorine solution, ammonia solution, amine, aldehyde, ketone, methanol, chelating agent, dispersant, nitride, nitrate, sulfide, sulfate, and the like dissolved in water or some other solvent may be used. Further, gaseous feedstocks such as ozone, air, chlorine dioxide, oxygen, carbon dioxide, carbon monoxide, argon, krypton, bromine, iodine, etc., each in predetermined amounts based on fluid remediation project objectives, may be employed. For solid compounds, the additive port 112 is shown. The injection of the desiccant may be performed by manipulating a valve 142 coupled to the additive port 112.

Still referring to fig. 1, the port 112 for introducing an agent into the repair channel 101 may introduce an oxidizing agent into the flow-through channel at or near the localized constriction. In the illustrated example, the port can be configured to allow introduction of the oxidant into the fluid in the partial flow constrictor. It is to be understood that the ports may be configured to introduce oxidant into the repair channel 101 not only at the partial constriction, but also along a region between the partial constriction and the region entering the cavitation zone where cavitation bubbles are formed (including the end points).

Still referring to fig. 1, and moving down the rehabilitation channel 101, additional sensors such as flow meters 114 are placed along the path. In the pre-cavitation zone, the flow meter is configured to quantify the bulk fluid motion to allow the PLC to calculate cavitation variables, which is discussed in more detail with reference to fig. 9. Once the contaminated water enters the cavitation zone 144, the fluid undergoes varying degrees of cavitation. Cavitation zone 144 may include: a first air injector 116 configured to inject air into the repair channel 101; a reactor plate 146; a second air injector 120; and a control valve 124 for controlling the proportion of flow through the cavitation zone 144 and for controlling the mean residence time of the fluid in the rehabilitation channel 101.

Still referring to fig. 1, first air injector 116 and second air injector 120 are configured to introduce cavitation in the fluid to form a vapor cavity (i.e., a small liquid-free zone, bubble, or void) in the liquid, which occurs when the fluid is subjected to rapid changes in pressure that result in the formation of a cavity in which the pressure is relatively low. In this manner, the injector serves to enhance the chemical reaction and propagate the reaction due to the formation of free radicals induced in the process by dissociation of the vapor trapped in the cavitation bubbles.

Still referring to fig. 1, a reactor sheet 146 is disposed within the rehabilitation channel 101 between the first air injector 116 and the second air injector 120. The reactor plate discussed in more detail in connection with fig. 8 is configured to introduce further cavitation such that a plurality of microbubbles having high volatility are present in the cavitation zone 144. When these microbubbles collapse, instantaneous pressures of up to 500 atmospheres and instantaneous temperatures of about 5000 degrees K are generated in the fluid. This phenomenon accomplishes several important chemical reactions: (1) H2O dissociates into OH radicals and H + atoms; (2) chemical bond cleavage of complex organic hydrocarbons; and (3) the long chain chemical species are oxidized to simpler chemical components before being irradiated downstream by the ultraviolet radiation, thereby further facilitating the oxidation process.

Still referring to fig. 1, an additional valve 124, which in the present embodiment is a butterfly valve, but may comprise other types of valves in other embodiments, is arranged in the rehabilitation channel 101 to reduce the head pressure when fluid needs to flow out to the outlets 104A-E. As with the other valves in the system, valve 124 is communicatively coupled to the PCL so that it is fully autonomous.

Still referring to FIG. 1, once the fluid has passed through cavitation zone 144, it will be fed through repair channel 101 toward RO membrane 152. The RO pump 160 is coupled to the remediation channel 101, ensuring that the appropriate amount is produced so that RO can occur across the RO membrane 152. Once at the output ports 104A-E, the fluid will pass through to the RO membrane 152, where it will undergo RO. When contaminated water enters the RO membrane 152 under pressure (sufficient to overcome osmotic pressure), water molecules pass through the RO membrane 152 and salts and other contaminants are not allowed to pass through and are discharged through the concentrate stream 162 and stored in the concentrate container 156. Permeate that is able to pass through the RO membrane 152 will pass through the permeate passage 154 and will be stored in the permeate container 150.

It was found that the RO filter fouled at a significantly slower rate and extended the membrane life significantly once the fluid passed through the cavitation reactor of figure 1. Further, it was found that after treatment of brackish water at 7MG per day to potable water, the system recovered between 55-65% RO concentrate (which was previously untreatable) and did not foul the membranes. A table as shown in table 1, wherein each vertical axis represents one week:

TABLE 1

When the RO is run alone, the filter does not foul at nearly the same rate, as will be discussed in connection with fig. 2-4.

Referring now to FIG. 2, a block diagram of a fluid remediation and/or treatment system incorporating hydrodynamic cavitation in accordance with an embodiment of the present invention is shown generally at 200. A water source 102 is provided that is pumped to or otherwise received by the hydrodynamic cavitation reactor 204. In the current embodiment, hydrodynamic cavitation is discussed. However, in alternative embodiments, it should be noted that other types of cavitation may be used with the present system and method, such as, but not limited to, acoustic cavitation and the like. Once the fluid undergoes cavitation in the hydrodynamic cavitation reactor 204, it is then received by a second fluid treatment system 208, which in this exemplary embodiment includes any system that utilizes a filter with a membrane to remediate contaminated water.

An example of wastewater treatment using membrane technology is RO. RO may utilize a film, such as a spiral wound element, comprising a sandwich of two film sheets, wherein the inserted permeate carriers are glued together and a feed spacer is inserted between the opposing film surfaces to complete the film package. The membrane package is wrapped around a perforated center tube through which the permeate exits the element. In a typical setup, the membrane will collect the permeate which acts as a "fouling layer". The fouling layer is typically composed of microbial communities, salts and inorganics (e.g., Al, As)、Ch、Co、Mg、BaSO₄O, S, Ni, P, Si, Fe, Ba, Sr, etc.).

After undergoing cavitation in reactor 204, the constituents in the brackish or brown water change their molecular structure and/or the charge of the molecules of the precipitate so that they disperse "naturally" and do not clog or foul the membrane. In this manner, as a pretreatment method and remediation technique, cavitation of the fluid or even cavitation of the concentrate after the first pass through the RO membrane reduces the likelihood of the RO membrane becoming clogged or fouled. If cavitation is used at the "first pass," RO provides for efficient pretreatment of water (for complete or partial removal of potential contaminants such as particulates, colloids, and organic matter).

The accumulation on the outside of the filter was found to consist of a fine white powder containing a small amount of larger aggregates and very similar in appearance to corn starch. The kinetics were analyzed by ICP/OES to detect the presence of inorganic components in the sample. Given the results of the solubility test, the powder is suspected to be a heterogeneous mixture of insoluble salts. Thus, any metal component detected by elemental analysis can be considered a cationic species in these salt crystals. To date, the most abundant metal found is calcium, followed by magnesium and potassium. The molar ratio between these metals was determined as follows: calcium to magnesium (mol: mol) 18.6:1 and calcium to potassium (mol: mol) 114: 1. Traces of the following metals (each less than 1ppm) were also detected: barium, cobalt, copper, molybdenum, nickel, titanium, vanadium, zinc, and silver. The instrument detects the following elements and produces reliable spectra, but we cannot quantify them: carbon, sulfur and phosphorus.

To determine the anionic component of the powder, small samples were analyzed by Ion Chromatography (IC). The anions tested were fluoride, chloride, nitrite, sulfate, bromide and phosphate. Since nitric acid was used to dissolve the powder, we could not test for nitrate.

Based on the available data, it was concluded that the powder in question was composed mainly of calcium sulphate (> 90%) and magnesium sulphate, as well as traces of the above metals constituting the rest of the powder. Although this conclusion was mainly drawn by qualitative means, it is supported by the observed empirical data and the known properties of calcium sulfate. The reported value of calcium sulfate solubility product (KSP) is 9X 10-6, which is consistent with our observation that the powder is slightly water soluble. Both calcium sulfate and magnesium sulfate also appear as white powders, which match the physical appearance of the powder as analyzed by the laboratory.

Finally, there appears to be a known source of calcium and magnesium ingress into the hydrostatic cavitation device based on data from the input stream. Water quality analysis of the concentrate input stream found calcium and magnesium to be present at very high levels. There appears to be a process by which these two cations react with sulfate to form insoluble aggregates during hydrostatic cavitation, which helps to avoid filter fouling.

Referring now to FIG. 3, a step-wise flow diagram of a method for performing fluid remediation incorporating hydrodynamic cavitation in accordance with an embodiment of the present invention is shown generally at 300. In this system, contaminated water from a water source 302 is pumped into or received by a cavitation reactor 304. Once RO membrane 306 receives contaminated water that has undergone cavitation, it undergoes reverse osmosis and the filtered production water is sent to production storage tank 308 and the concentrate stream is sent to storage tank 310 along with fluid not ready for consumption. At the holding tank 310, the fluid settles and the particles settle to the bottom. The fluid with the concentrate is then sent back to cavitation reactor 304 where it undergoes hydrodynamic cavitation as described herein before being reprocessed by RO membrane 306.

During the test, not only about 55% -65% of the fluid is recovered and made available for production of water, after the contaminated water stream is advanced through the cavitation reactor 304, the RO membranes 306 do not foul as they would if the contaminated water had not experienced cavitation at all. Instead, the pressure on the membrane is maintained at an approximately steady pressure throughout the daily cycle. In the "normal" case in RO, as the precipitate accumulates, the pressure on the membrane builds up over the entire process. Inspection of the filter shows that once the contaminated water travels through cavitation reactor 304, the fouling layer does not accumulate on RO membrane 306, or at least at a much lower rate. RO membrane 306 comprises a plurality of membranes, which in the exemplary embodiment have pore sizes ranging from 0.0001 μm to 0.001 μm, such that almost all molecules except water can be retained, and the required osmotic pressure is significantly greater than other forms of filtration due to the size of the pores. Thus, particle accumulation may occur and foul the RO membrane 306, and also result in loss of capacity and increased pressure until a failure condition may sometimes occur.

Still referring to FIG. 3, in this exemplary embodiment, contaminated water from water source 302 is sent directly to cavitation reactor 304. However, in an alternative embodiment, contaminated water from the water source 302 may first be subjected to RO and passed through its own RO membrane before being sent to the cavitation reactor 304.

Referring now to fig. 4, a front view of a membrane used in reverse osmosis in accordance with one embodiment of the present invention is generally indicated at 400. In the current embodiment, films 402 and 404 are shown. Membrane 402 is operated with fluid that has not undergone a cavitation process as described herein, while membrane 404 shows a membrane through which fluid that has undergone a cavitation process as described herein has traveled. It can be seen that fouling layers and their particles 406 accumulate on the inner part of the membrane, whereas in the membrane 404 the smallest fouling layer particles accumulate on the outer part of the membrane 408. This means that LP membranes can be used compared to HP membranes, resulting in significant cost savings.

Referring now to FIG. 5, a flow diagram illustrating an exemplary method of cavitation-based water remediation, in accordance with one embodiment of the present invention, is indicated generally at 500. In the current embodiment, the method 500 may include: water is supplied to the restoration path using a pump such that contaminated water flows through the restoration path from the inlet, step 502.

Still referring to fig. 5, the method 500 may further include injecting at least one reagent into the permeate water using an injection port in fluid communication with the repair channel, step 504. The method 500 may further include introducing 506 a pulse of air into the fluid using an air actuator in fluid communication with the repair channel downstream of the injection port. The method 500 may further include flowing a fluid through the reactor sheet to create a rotational flow, step 508.

Still referring to fig. 5, the method 500 may further include introducing 510 an air pulse into the permeate water using an air actuator located downstream of the injection port in fluid communication with the repair channel at a second location. The method 500 may further include generating 512 at least one or more, and typically a plurality of, swirling vortices and cavitation pockets in the permeate water within the restoration passage.

Still referring to fig. 5, method 500 may further include regulating the flow of the fluid using a flow regulating valve disposed within the repair passage and in electronic communication with the air actuator, the flow regulating valve configured to optimize pressure to increase the number of cavitated pockets within the liquid, step 516. The method 500 may further include outputting the remediated permeate to a reverse osmosis remediation system (step 516), and outputting permeate from the reverse osmosis system to a production storage tank, and flowing concentrate from the reverse osmosis system into a holding tank for further reprocessing through the remediation channel and the reverse osmosis system (step 518).

Example 1

This example is for the purpose of illustrating embodiments and should not be construed as limiting.

Referring now to FIG. 6, an alternative embodiment of a large scale commercial implementation of a repair system utilizing cavitation is generally designated 600. This alternative embodiment contemplates the use of multiple columns of the system described herein. By linking multiple trains together, this allows for the highest quality remediation by passing the concentrate produced in trains a and b through its own reverse osmosis process. This is considered a multi-stage system where the concentrate from the first two stages becomes the feed water for the third stage. The use of additional stages allows for increased permeate water recovery from the system. In even more alternative embodiments on a larger scale, more than 2 stages may be used before the concentrate is collected and processed.

Starting from the existing train a, contaminant water is obtained from the supply 602. The pump 604 pushes the contaminated water towards a reactor 606 comprising a hydrodynamic cavitation system and a centrifuge 608. Once the contaminated water passes through centrifuge 608, the solids are transferred to solids storage tank 610 and the remaining water is then sent to column a RO membranes 614 via pump 612, which is designed to provide sufficient pressure to allow reverse osmosis to occur as the water passes through column a RO membranes 614. Once through the RO membrane 614, the permeate is sent by pump 616 to permeate storage tank 618 while the concentrate is sent by pump 620 to concentrate supply 622.

Still referring to fig. 6, while existing column a is operating, existing column B is also operating. Column B begins when contaminated water is obtained from feeder 626. Pump 628 then pushes the contaminated water towards reactor 630 and centrifuge 632, where hydrodynamic cavitation occurs. The solids are transferred to solids storage tank 636 and the remaining water is sent to row B RO membranes 646 by pump 634. Much like column a, pump 634 will provide sufficient pressure to allow reverse osmosis to occur as the water passes through RO membranes 646 of column B. Once through the RO membrane 646, the permeate is sent to the permeate reservoir 640 by the pump 624, while the concentrate is sent to the concentrate feeder 622 by the pump 638.

Still referring to fig. 6, once both column a and column B are completed and concentrate from both columns is sent to the concentrate feeder 622, column C will be executed. Reactor 642 receives concentrate from concentrate supply 622, which is then transported through RO membranes 648 of train C by pump 644. As with columns a and B, the pump 644 is designed to generate sufficient pressure to allow reverse osmosis to occur as the concentrate passes through the RO membrane 648 of column C. Permeate produced as a result of passing through RO membranes 648 of column C will be sent to permeate reservoir 652 by pump 650, while the remaining concentrate will be sent to concentrate reservoir 656 by pump 654.

Referring now to FIG. 7, a table illustrating data obtained from a test case utilizing the systems and methods provided herein to perform repair and cavitation is generally indicated at 700. Table 700 shows the operating pressures for each day during the test period. The membrane operating pressure is an indicator of the fouling capacity of the membrane. At the start of each test, the operating pressure was in the range of 330 to 350 psi. The pressure increased to 380 to 390psi over the first four hours of each test and then remained stable throughout the remainder of the test. If the membrane becomes fouled, the operating pressure will gradually increase during the course of the test period and will not return to the baseline value at the end of each test run. During the test period, there was no measurable increase in operating pressure, and thus the test data did not show significant membrane fouling.

Referring now to FIG. 8, a front view of a reactor plate for use in a system according to one embodiment of the present invention is generally indicated at 800. Referring back to fig. 1, a substantially homogeneously mixed stream is directed from the air injector 116 to the reactor plate 146. The reactor plate 146 includes a central aperture of a predetermined size through which fluid passes. The uniform stripes 802 are arranged on the face of the reactor sheet 146, the number of which is predetermined based on the use case, and the uniform stripes are configured to uniformly disperse the fluid. In some embodiments, the striations 802 are circular rings that form respective peaks and valleys on predetermined portions of the face of the plate. In the embodiment shown generally at 800, the striations cover approximately half of the plate from the outer radius inward. In some alternative embodiments, the striations may act as seals with respect to the cavitation zone. As can be seen in fig. 1, the flanges allow for easy replication of these sections.

Still referring to fig. 8, the swirl imparting section 804 is disposed inwardly toward the center of the plate 146 and includes a leading edge portion that first slopes upwardly and rearwardly and then curves in a continuous convex rearward curve, having valleys 808 and peaks 810 that merge to extend generally horizontally rearwardly to an upper edge portion. These peaks 810 may be referred to as "lobes". This formation ensures that the bubbles begin to form in a small enough size to generate a long range of hydrophobic forces that promote bubble/particle attachment and to generate bubbles of optimal size and quantity in a constantly changing mixing environment. The reactor sheet 146 increases the amount of hydroxyl radicals (which are generally capable of degrading and/or oxidizing organic compounds in the fluid) and generates a large amount of oxidant contained within and/or associated with the cavitation bubbles.

The reactor plate 146 may be formed of a material that is relatively impermeable to the cavitation portion, such as a metal alloy, or in some embodiments, an elastomeric material having elasticity. The reactor sheet 146 may be embodied in a variety of different shapes and configurations. For example, the plate may be conical, including a conical surface that induces swirl, or may be fully recirculating as shown. It will be appreciated that other shapes may be employed to varying degrees.

Referring now to fig. 9, a schematic diagram of a fluid remediation system utilizing hydrodynamic cavitation and an intelligent platform and automated hardware/software arrangement in accordance with an embodiment of the present invention is shown generally at 900. "Intelligent platforms" typically involve controls such as programmable logic controls, high performance and high performance system (e.g., PAC system) controllers, etc., having redundant availability, extensible open architecture, scalable CPUs, etc. Furthermore, in embodiments of the present invention, use is made of

Distributed I/O to maximize efficiency and data distribution has I/O flexibility and connects to the entire range of I/O from simple discrete I/O to secure and process I/O.

As shown in FIG. 9, the PLC902 is electrically coupled (e.g., hardwired, wireless, etc.) to a plurality of controllers 904, 906, 908,Etc.), each controller is coupled to various valves and sensor arrays. PLC902 is configured to execute software that continuously acquires data regarding the status of input devices to control the status of output devices. As is well known, a PLC typically includes a processor (which may include volatile memory), volatile memory including applications, and one or more input/output (I/O) ports for connecting to other devices in the automation system. Furthermore, in PLC, context awareness for processes available on the control level for business analysis applications can be lost. The platform may further include higher level software functionality in a data acquisition and monitoring control (SCADA), Manufacturing Execution System (MES), or Enterprise Resource Planning (ERP) system. Alternatively, the PLC can be an "intelligent PLC" that includes various components, which components areMay be configured to provide various enhanced functionality in control applications. For example, in some embodiments, the intelligent PLC includes deeply integrated data history and analysis functions. This technique is particularly applicable to, but not limited to, various industrial automation environments for water remediation. In operation, automation system context information may include, for example, one or more of the following: an indication of the device that produced the data, a structural description of the automation system including the intelligent PLC, a system operating mode indicator, and information about the product produced when generating the contents of the process image area. Additionally or alternatively, the contextualized data may include one or more of: a description of the automation software used by the intelligent PLC, or a status indicator indicating the status of the automation software when generating the contents of the process image area.

Still referring to fig. 9, the PLC is electrically coupled to the pump 124 and fluid source 908, the sensor housing 106, the valve 910, the plurality of injector coils 110, the additive port 112, and the other sensing array 114. An additional down line controller 904 is communicatively coupled to the PLC and is further in communication with the additive ports 112 and 138. In an alternative embodiment of the invention, the sensor array 106 is configured to acquire all relevant properties of the fluid and send this information to the PLC of 902. Based on the nature of the fluid, the PLC is configured to direct valve 914 to release into the stream an agent that supports the remediation process. In some embodiments, PLC902 carries predetermined information regarding the quality of the fluid. As an example, different types and combinations of precursor compounds in solid, liquid or gas phase, such as compounds that may contain halide salts (such as fluorine, chlorine, bromine, iodine), sulfate, sodium or potassium, etc., introduced as solids, or dissolved in water or other solvents, may be employed depending on the type of fluid treatment process selected, the contaminants to be treated, the existing water quality, the desired water quality, and other variables. An additional sensor array 912 is provided for testing and acquiring data about the treated fluid and ensuring that the proper pressure and flow rate can be provided.

The first air injector 116 is in communication with an additional controller 906, which in turn is in communication with the PLC 902. In an alternative embodiment of the present invention, PLC902 is configured to control air pressure based on a desired degree of cavitation. The controller 906 also communicates with the reactor sheet 146 and baffles (not shown) to rotate and tilt the reactor sheet to vary the degree of cavitation. Similar to the first air injector, the second air injector 120 and the control valve 124 are in communication with the controller 906 for similar purposes.

Still referring to fig. 9, additional actuators 918 may be employed, as may optional sensor arrays 920 and UV reactors 922, each of which are connected to a controller before passing through RO membranes 924 and becoming end-use, reconditioned fluid 926.

The first and second air injectors are configured to introduce cavitation in the fluid to form a vapor cavity (i.e., a small liquid-free zone, bubble, or void) in the liquid, which occurs when the fluid is subjected to rapid changes in pressure that result in the formation of a cavity in which the pressure is relatively low. In this manner, the injector serves to enhance the chemical reaction and propagate the reaction due to the formation of free radicals induced in the process by dissociation of the vapor trapped in the cavitation bubbles.

The reactor plate 146 is disposed in line 101 between the first and second air injectors and is in communication with the PLC902, and the PLC902 is configured to tilt the reactor plate 146 in different directions (e.g., 15 degrees). The reactor plate, discussed in more detail in connection with fig. 2, is configured to introduce further cavitation such that a plurality of microbubbles having high volatility are present in the cavitation zone 144.

An additional valve 124 (e.g., a butterfly valve) is disposed in the line to reduce the head pressure when it is desired to discharge fluid to the outlet 104. As with the other valves in the system, valve 124 is communicatively coupled to the PCL so that it is fully autonomous.

While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment. Rather, the invention is to cover all such different modifications and equivalent arrangements as fall within the spirit and scope of the appended claims.

Although specific features of various embodiments of the invention may be shown in some drawings and not in others, this is for convenience only. In accordance with the principles of the invention, features of one drawing may be combined with any or all of the features of any other drawing. The words "including," "comprising," "having," and "with," as used herein, are to be interpreted broadly and comprehensively and are not limited to any physical interconnection. Moreover, any embodiments disclosed herein are not to be interpreted as the only possible embodiments. Rather, modifications and other embodiments are intended to be included within the scope of the appended claims.

Claims (15)

1. A method for preventing fouling of a membrane in a fluid treatment system having at least one membrane, the method comprising:

hydrodynamic cavitation of the fluid stream prior to injecting the fluid stream into the fluid treatment system and through the at least one membrane;

wherein after undergoing hydrodynamic cavitation in the cavitation reactor, solid components in the fluid change their (i) molecular structure, (ii) charge, or both, such that the components repel each other and disperse around the edges of the membrane to prevent fouling.

2. The method of claim 1, further comprising pumping the fluid to be treated into a first reverse osmosis train to produce a concentrate, wherein the reverse osmosis train comprises a plurality of membranes, the at least one membrane being one of the plurality of membranes.

3. The method of claim 2, further comprising receiving the concentrate at a hydrodynamic cavitation reactor and introducing air pulses into the concentrate using an air actuator.

4. The method of claim 1, further comprising treating the concentrate at the hydrodynamic cavitation reactor and transporting the concentrate through at least one membrane, wherein the at least one membrane comprises a first RO membrane or a second RO membrane.

5. The method of claim 1, after hydrodynamic cavitation of the fluid, advancing the fluid through a centrifuge.

6. The method of claim 1, wherein the fluid is a concentrate that is a product of a first RO process, and the concentrate travels through the cavitation reactor before traveling through a second RO process.

7. The method of claim 6, wherein after passing the concentrate through the cavitation reactor, a solids mixture is produced comprising a calcium to magnesium ratio of 18.6:1 and a calcium to potassium ratio of 114: 1.

8. A system for preventing fouling of a membrane in a fluid treatment system having at least one membrane, the method comprising:

a hydrodynamic cavitation reactor for cavitating a fluid stream prior to injection into the fluid treatment system and across the at least one membrane;

wherein after undergoing hydrodynamic cavitation in the cavitation reactor, solid components in the fluid change their (i) molecular structure, (ii) charge, or both, such that the components repel each other and disperse around the edges of the membrane to prevent fouling.

9. The system of claim 8, further comprising: at least one pump configured to pump a fluid to be treated into a first reverse osmosis train to produce a concentrate, wherein the reverse osmosis train comprises a plurality of membranes, the at least one membrane being one of the plurality of membranes.

10. The system of claim 9, wherein the reactor receives the concentrate and introduces air pulses into the concentrate using an air actuator.

11. The system of claim 8, further comprising: a second membrane after the hydrodynamic cavitation reactor for treating the concentrate.

12. The system of claim 8, further comprising: a centrifuge in fluid communication with the cavitation reactor, the centrifuge configured to remove particles from the fluid.

13. The system of claim 8, further comprising: a second hydrodynamic cavitation reactor, and fluid inlets configured to transport the concentrate through at least one membrane, wherein the at least one membrane comprises a first RO membrane or a second RO membrane.

14. The system of claim 13, wherein after passing the concentrate through the cavitation reactor, a solids mixture is produced comprising a calcium to magnesium ratio of 18.6:1 and a calcium to potassium ratio of 114: 1.

15. The system of claim 8, wherein the membranes comprise low pressure membranes.

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